ESTA soil tests

Extended Soil Test Analysis

Can we understand the soil as a living organic entirety? Not merely as an accumulation of a certain amount of macro-and micro elements. Soil is like the living skin of our planet and should be looked upon and treated accordingly. A most important task of soil assessment according to the system of Dr Balzer is the integral, dynamic knowledge of the specific site conditions. This is the reason why the extended soil test comprehends and assesses the soil with 14 determinants, instead of a quick test’s 4 or 5. These 14 determinants will give you knowledge of:

physical facts, such as soil structure, soil compaction, cation exchange capacity, air and water household, salt content and soil management

environmental aspects, such as a first indication of heavy metal contamination (zinc, copper, manganese)

Biological soil activity (see below) is to be understood as the result of the longterm, site specific humus dynamics (balance or imbalance of humus buildup for future yields and humus decomposition for present yield); the quality of the humus determins the site specific soil fertility and how to work with it in a sustainable way.

Supplying Soil Samples

The samples (approx. 200g) may be taken during the whole year. Each paddock, field or garden plot should be covered by one mixed sample, whereby several samples (4-6) should be taken diagonally over the area and each one should be dug a spade depth from 0 – 300 mm. All organic material such as straw, grass, wood or cardboard is to be separated out. Mix all samples of each paddock in a bucket and then take out one mixed sample of ca. 200 grammes. Please enclose with it the date of sampling, the crop grown, the crop rotation and previous fertiliser and/or compost applications. The sample should be airdry and posted in a plastic or sealed paper bag to Sustain-Ability.

Costs per sample are $130 + GST

Biological soil activity

A parameter for the biological soil activity is essential for any farmer interested in sustained soil fertility which derives from humus. As organic farmers we are mainly interested in the stabilised form of humus, which is a product of advanced decomposition of organic residues and products, resynthesised by microorganims and is itself of a colloidal nature. Such humus contains amino, hydroxyl and carboxyl humic compounds which give rise to a high cation exchange capacity and builds clay-humus complexes which contribute to soil structure and guarantee a slow release of energy and nutrients in the form of inorganic ions. To quantify the stabilised form of humus we need a figure relating directly to the biological soil activity. The parameter for biological soil activity in ESTA derives from 14 different values and their correlation to each other.

The phosphorus value, especially provides a reliable indicator of the nutrient levels and their mobilisation, when it is measured in soluble phosphorus (shown in the P-Na-acetate figure), available phosphorus (in P-double lactate figure and the phosphorus reserve in the soil in the P-citrate figure) – all 3 figures are in ESTA. These figures and their correlation facilitate the evaluation of the biological soil activity and are adequate recommendations for fertiliser application.

A classification guide has been developed to match the New Zealand soil conditions and farm location criteria.